This was asked on another user group after a pilot experienced a large loss of power using a traditional exhaust.

In a traditional exhaust, gases are shot at each other and have to diffuse through a flame tube to exit. When that flame tube breaks down, it is hoped that the chunks are small enough to not block the exit from the muffler and thereby causing a potentially dangerous power loss or new hole in the muffler for your air pump (the engine) to relieve the pressure it created.

One of the engineered “improvements” of the Power Flow over traditional Elano style (and other standard) exhaust systems is to allow an uninterrupted pathway for the exhaust gases in the muffler area. The PFS muffler design is a 14 inch stainless steel perforated tube that has a 2.0 inch diameter. The gases exit the 4 to 1 collector, go down a 2.0 inch pipe and enter the muffler area and continue down the 2.0 inch inner diameter of the perforated tube. If you look at the PFS muffler, it has expansion from a 2.0 inch area to a 3.5 diameter. The perforated tube butts up against the 2.0 area, with the remaining 1.5 inches dedicated to an automotive type sound suppression material. The inner wrapping that is directly exposed to the exhaust gases is made up of INOX stainless steel fibers, with the outer layer a high density BASALT wrap. It looks a little like fiberglass, but it is brown in color.

This high density wrap around the perforated tube is designed to be sacrificial. It will, over time, break down into very tiny hairs and blow out the tail pipe. The structure of the inner stainless steel tube is designed to stay intact and isn’t standing in the way of the gas pathway. On condition (we have seen between 500 and 1500 hours) you remove the entire muffler insert, and replace it with another for about 15 minutes labor and $120.00 for the part. This can be done in the field, while the exhaust is on the plane, if you want. No overhaul or sending the muffler out for rebuild.

While nothing is impossible, I’m not aware of any reported cases (in over 3200 exhausts and counting) of the same kind of partial or total muffler blockage that was reported here on the GG. The PFS muffler was designed to minimize this potentially dangerous problem.

To inspect the PFS muffler, you shine a light up the tailpipe. You are looking to make sure that the inner tube is intact and that you can see the light reflecting back from stainless steel hairs. I recommend that every PFS owner take 10 seconds and do this during pre-flight.